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Sebanyak 25 mL larutan  yang mempunyai pH = 11 diencerkan hingga volume 250 mL. Jika , pH larutan setelah diencerkan adalah ....

Pertanyaan

Sebanyak 25 mL larutan begin mathsize 14px style N H subscript 4 O H end style yang mempunyai pH = 11 diencerkan hingga volume 250 mL. Jika begin mathsize 14px style K subscript b space N H subscript 4 O H space equals space 1 cross times 10 to the power of negative sign 5 end exponent end style, pH larutan setelah diencerkan adalah ....space 

  1. 10undefined 

  2. 10,5undefined 

  3. 11undefined 

  4. 11,5undefined 

  5. 12undefined 

S. Lubis

Master Teacher

Jawaban terverifikasi

Pembahasan

Diketahui:

larutan begin mathsize 14px style N H subscript 4 O H end style = 25 mL mempunyai pH = 11 diencerkan hingga volume 250 mL

begin mathsize 14px style K subscript b space N H subscript 4 O H space equals space 1 cross times 10 to the power of negative sign 5 end exponent end style

Ditanya:

pH larutan setelah diencerkan

Jawab:

1. Menghitung Konsentrasi begin mathsize 14px style N H subscript 4 O H end style sebelum pengenceran (saat pH = 11):

begin mathsize 14px style pH equals 11 pOH equals 14 minus sign pH pOH equals 14 minus sign 11 pOH equals 3  open square brackets O H to the power of minus sign close square brackets equals 10 to the power of negative sign 3 end exponent open square brackets O H to the power of minus sign close square brackets equals square root of K subscript b cross times open square brackets N H subscript 4 O H close square brackets end root 10 to the power of negative sign 3 end exponent equals square root of 1 cross times 10 to the power of negative sign 5 end exponent cross times open square brackets N H subscript 4 O H close square brackets end root open parentheses 10 to the power of negative sign 3 end exponent close parentheses squared equals open parentheses square root of 1 cross times 10 to the power of negative sign 5 end exponent cross times open square brackets N H subscript 4 O H close square brackets end root close parentheses squared 10 to the power of negative sign 6 end exponent equals 10 to the power of negative sign 5 end exponent cross times open square brackets N H subscript 4 O H close square brackets open square brackets N H subscript 4 O H close square brackets equals 10 to the power of negative sign 1 end exponent space M end style

2. Menghitung Konsentrasi begin mathsize 14px style N H subscript 4 O H end style setelah pengenceran:

begin mathsize 14px style M subscript 1 cross times V subscript 1 double bond M subscript 2 cross times V subscript 2 10 to the power of negative sign 1 end exponent space M cross times 25 space mL double bond M subscript 2 cross times 250 space mL M subscript 2 equals fraction numerator 10 to the power of negative sign 1 end exponent space M cross times 25 space mL over denominator 250 space mL end fraction M subscript 2 equals 10 to the power of negative sign 2 end exponent space M end style

3. Menghitung pH larutan begin mathsize 14px style N H subscript 4 O H end style setelah diencerkan:

Error converting from MathML to accessible text.

Jadi, jawaban yang tepat adalah B.undefined


 

155

5.0 (3 rating)

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